1. Field
This disclosure relates to policy systems, more particularly to interactions between policy systems and call admission control systems.
2. Background
Wholesale dial and voice over data networks are deployed to manage a target number of active sessions, or calls. For ease of discussion, voice over data networks calls will be referred to as Voice over Internet Protocol (VoIP) calls, with no intention to limit the implementation of data networks to IP networks. Networks that provide access to both dial and VoIP network services will be referred to as Any Service Any Port (ASAP) networks.
Wholesalers own the networks and access to the networks to customers, typically network service providers such as America OnLine (AOL). These sales of access are typically governed by service level agreements (SLA). The wholesaler must purchase enough equipment, ports and circuits, with enough redundancy to be able to honor the SLAs.
Networks are typically built for peak steady state operations, taking into consideration the bandwidth necessary for transferring call data through the network. Many wholesalers overlook transients that can impact their network. They rely on vendors to provide some basic form of call denial or ‘least cost’ routing as one safe guard for a particular node in the system to avoid catastrophic events for the node.
One such safeguard currently in use is Call Admission Control (CAC). A typical CAC system has ‘high water’ marks, or thresholds, set for sub-system components such as central processing unit (CPU) utilization, memory utilization, etc. After the threshold is exceeded, the system will reject new requests.
However, one of the issues with current CAC systems is that they are reactive. They only act after the threshold is exceeded. If the threshold is set too low, the platform will cycle in and out of reject mode. This lowers the ‘average’ call success rate. If the threshold is set too high, the platform will accept too many calls onto its circuits, impacting service for many calls. Additionally, CAC systems typically have a timer that has to expire for the system to return to accepting calls. If the threshold is triggered for an instant, all calls will be denied until the timer expires. It would be advantageous to make call acceptance decisions before resources were allocated to the call. Similarly, it would be better if the decisions were made in a more dynamic manner, without having to wait for timers to expire.
Another issue with current CAC systems is that it operates on the platform level. The platform may accept calls into a network at a rate that cannot be sustained by other platforms required to manage setting up the call. It would be helpful if the CAC-type limitations could be set and managed at the system level. The decision should be controlled sufficiently upstream of call setup so that call redirection, hunting and similar processes could allow selection of a different set of resources.
An additional issue with the platform-level CAC systems is that they are static and sub-system oriented. As networks are upgraded, and the system and service mix changes, it increases the difficulty of provisioning the network. Each CAC sub-system limit has to be individually adjusted across the entire network. Management of these types of limits in a more centralized manner would seem more practical.